Scholars Day: April 11, 2012

Spatiotemporal Variation in Fatty Acid Signatures of Lake Michigan Spottail Shiner (Notropis hudsonius)

The pelagic food web of Lake Michigan has been the main focal point of ecological studies because of the importance of commercial and sport fisheries in this oligotrophic system. However, recent introductions of non-native species, mainly dreissenid mussels (zebra mussel Dreissena polymorha and quagga mussel Dreissena rostrisformis) and round gobies (Neogobius melanostomus), have altered trophic ecology directing more attention to the coastal (nearshore) areas. Still these coastal zones have been understudied, especially the assemblage of the recently altered nearshore food web. To better understand the resulting changes to the nearshore trophic structure in Lake Michigan, fatty acid signatures (FAS) of spottail shiner Notropis hudsonius, a prey fish for many fish species, were analyzed from eleven sites around Lake Michigan (Wisconsin, Illinois, Indiana, and Michigan) pertaining to two habitats (rocky or sandy) and three seasons (spring, summer, and fall). Unlike diet analysis of stomach contents, FAS provide insights into longer term feeding habits of consumers based on the degree of similarity between their FAS and those of their prey. Using multivariate statistics, we found differences in FAS among groups demonstrating the heterogeneous character of spottail shiner feeding throughout Lake Michigan and the importance of FAS analysis as a tool to explore feeding ecology of freshwater fish.

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